There was to be another episode about quantum, but today a special edition.A beautiful June day was already heading west when my wife informed me that on According to TV Republic, the spinner of our baby is the work of Satan. I always say that Facebook should not be more than once in a few days. It is more difficult then to find the information that is shared by your friends is not relevant and littering. For example, for the revelations about the evilness of spinner.
What is this toy? I confess that I had no idea what it could be until I was forced by my son to pay 25 gold for a piece (they are certainly cheaper) and to purchase a flat, symmetrical “something” with the middle of the bearing mounted. Thanks to the toy bearing, it is spinning for a long time and … its the only function.
This toy gives an amazing opportunity to observe the so-called. Gyroscopic forces. But from the beginning. The physical size corresponding to the “amount of rotational movement” is the so-called. Moment of momentum. Those who do not know what it is, I refer to the note “Experience with the phone”. The direction of momentum is fairly arbitrary – but if the axis of rotation is at the same time the axis of symmetry of the object, then it is precisely that direction. That is the case with our spinner. When the plane of rotation is changing, the direction of momentum changes. And the moment of momentum can change only when the moment of force is activated. This is the equivalent of the second principle of dynamics for rotational motion – moment of force changes moment of momentum.
When we accelerate the toy – holding it in the middle with the index finger and thumb – and we will change the plane of rotation, we will feel the reaction of the toy. By changing the direction of the moment of momentum, we act on such forces that they will settle into the moment of momentum. The toy according to the third principle of dynamics works with opposing forces to ours, which we will feel “in the fingers”.
This happens not only in the case of a toy. Any engine rotors whose direction changes are also subject to gyroscopic forces. And as long as the spinner’s bearing is not apparently destroyed at this point, it can be a serious engineering problem for the rotor on an airplane.
Since you’ve been practicing a bit, it’s time for another experiment, which will require some plasticine and a two-piece spinner. This batman from the photo will give.
Above I wrote that for a symmetrical object the axis of rotation is the same as the momentum of momentum. So let’s try to distort this symmetry. I suggest to stick a bit of plasticine (the more the better, though too much can not advise, because it does not fit between the fingers). Attaching the same pieces on both sides will cause the center of gravity to be preserved, but the momentum of momentum will no longer be perpendicular to the plane of motion – here again for details, I refer to the note “Experience with the phone.” After twisting you will feel a gentle swing. That’s right – because the direction of momentum is slightly different from the axis of rotation, it changes all the time. As I have mentioned, this involves constant momentum. Reaction forces give the impression of swing.
The reverse process to our experiment – that is, the weight of the wheel, so that its moment of momentum coincides with the axis of motion, is called balancing and probably every driver saw him.
After a twist, a bit more, but more strongly than in the previous case, we feel “beat”. Just moment of momentum does not change direction, so it is not he who is responsible for the felt force. The confusion of the mass is different. Because the movement is circular and the masses are different on both sides, an unbalanced centripetal force appears. More precisely: to keep the axis of rotation, we have to pull the toy a little to “from sticky plasticine”. It feels like we have had to oppose the “beat”.
I encourage you to do independent experiments.